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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "ui/views/widget/root_view.h"
      6 
      7 #include <algorithm>
      8 
      9 #include "base/logging.h"
     10 #include "base/message_loop/message_loop.h"
     11 #include "ui/accessibility/ax_view_state.h"
     12 #include "ui/base/cursor/cursor.h"
     13 #include "ui/base/dragdrop/drag_drop_types.h"
     14 #include "ui/base/ui_base_switches_util.h"
     15 #include "ui/compositor/layer.h"
     16 #include "ui/events/event.h"
     17 #include "ui/events/keycodes/keyboard_codes.h"
     18 #include "ui/gfx/canvas.h"
     19 #include "ui/views/drag_controller.h"
     20 #include "ui/views/focus/view_storage.h"
     21 #include "ui/views/layout/fill_layout.h"
     22 #include "ui/views/view_targeter.h"
     23 #include "ui/views/widget/root_view_targeter.h"
     24 #include "ui/views/widget/widget.h"
     25 #include "ui/views/widget/widget_delegate.h"
     26 
     27 typedef ui::EventDispatchDetails DispatchDetails;
     28 
     29 namespace views {
     30 namespace internal {
     31 
     32 namespace {
     33 
     34 enum EventType {
     35   EVENT_ENTER,
     36   EVENT_EXIT
     37 };
     38 
     39 class MouseEnterExitEvent : public ui::MouseEvent {
     40  public:
     41   MouseEnterExitEvent(const ui::MouseEvent& event, ui::EventType type)
     42       : ui::MouseEvent(event,
     43                        static_cast<View*>(NULL),
     44                        static_cast<View*>(NULL)) {
     45     DCHECK(type == ui::ET_MOUSE_ENTERED ||
     46            type == ui::ET_MOUSE_EXITED);
     47     SetType(type);
     48   }
     49 
     50   virtual ~MouseEnterExitEvent() {}
     51 };
     52 
     53 }  // namespace
     54 
     55 // This event handler receives events in the pre-target phase and takes care of
     56 // the following:
     57 //   - Shows keyboard-triggered context menus.
     58 class PreEventDispatchHandler : public ui::EventHandler {
     59  public:
     60   explicit PreEventDispatchHandler(View* owner)
     61       : owner_(owner) {
     62   }
     63   virtual ~PreEventDispatchHandler() {}
     64 
     65  private:
     66   // ui::EventHandler:
     67   virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE {
     68     CHECK_EQ(ui::EP_PRETARGET, event->phase());
     69     if (event->handled())
     70       return;
     71 
     72     View* v = NULL;
     73     if (owner_->GetFocusManager())  // Can be NULL in unittests.
     74       v = owner_->GetFocusManager()->GetFocusedView();
     75 
     76     // Special case to handle keyboard-triggered context menus.
     77     if (v && v->enabled() && ((event->key_code() == ui::VKEY_APPS) ||
     78        (event->key_code() == ui::VKEY_F10 && event->IsShiftDown()))) {
     79       // Clamp the menu location within the visible bounds of each ancestor view
     80       // to avoid showing the menu over a completely different view or window.
     81       gfx::Point location = v->GetKeyboardContextMenuLocation();
     82       for (View* parent = v->parent(); parent; parent = parent->parent()) {
     83         const gfx::Rect& parent_bounds = parent->GetBoundsInScreen();
     84         location.SetToMax(parent_bounds.origin());
     85         location.SetToMin(parent_bounds.bottom_right());
     86       }
     87       v->ShowContextMenu(location, ui::MENU_SOURCE_KEYBOARD);
     88       event->StopPropagation();
     89     }
     90   }
     91 
     92   View* owner_;
     93 
     94   DISALLOW_COPY_AND_ASSIGN(PreEventDispatchHandler);
     95 };
     96 
     97 // This event handler receives events in the post-target phase and takes care of
     98 // the following:
     99 //   - Generates context menu, or initiates drag-and-drop, from gesture events.
    100 class PostEventDispatchHandler : public ui::EventHandler {
    101  public:
    102   PostEventDispatchHandler()
    103       : touch_dnd_enabled_(::switches::IsTouchDragDropEnabled()) {
    104   }
    105   virtual ~PostEventDispatchHandler() {}
    106 
    107  private:
    108   // Overridden from ui::EventHandler:
    109   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE {
    110     DCHECK_EQ(ui::EP_POSTTARGET, event->phase());
    111     if (event->handled())
    112       return;
    113 
    114     View* target = static_cast<View*>(event->target());
    115     gfx::Point location = event->location();
    116     if (touch_dnd_enabled_ &&
    117         event->type() == ui::ET_GESTURE_LONG_PRESS &&
    118         (!target->drag_controller() ||
    119          target->drag_controller()->CanStartDragForView(
    120              target, location, location))) {
    121       if (target->DoDrag(*event, location,
    122           ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH)) {
    123         event->StopPropagation();
    124         return;
    125       }
    126     }
    127 
    128     if (target->context_menu_controller() &&
    129         (event->type() == ui::ET_GESTURE_LONG_PRESS ||
    130          event->type() == ui::ET_GESTURE_LONG_TAP ||
    131          event->type() == ui::ET_GESTURE_TWO_FINGER_TAP)) {
    132       gfx::Point screen_location(location);
    133       View::ConvertPointToScreen(target, &screen_location);
    134       target->ShowContextMenu(screen_location, ui::MENU_SOURCE_TOUCH);
    135       event->StopPropagation();
    136     }
    137   }
    138 
    139   bool touch_dnd_enabled_;
    140 
    141   DISALLOW_COPY_AND_ASSIGN(PostEventDispatchHandler);
    142 };
    143 
    144 // static
    145 const char RootView::kViewClassName[] = "RootView";
    146 
    147 ////////////////////////////////////////////////////////////////////////////////
    148 // RootView, public:
    149 
    150 // Creation and lifetime -------------------------------------------------------
    151 
    152 RootView::RootView(Widget* widget)
    153     : widget_(widget),
    154       mouse_pressed_handler_(NULL),
    155       mouse_move_handler_(NULL),
    156       last_click_handler_(NULL),
    157       explicit_mouse_handler_(false),
    158       last_mouse_event_flags_(0),
    159       last_mouse_event_x_(-1),
    160       last_mouse_event_y_(-1),
    161       gesture_handler_(NULL),
    162       gesture_handler_set_before_processing_(false),
    163       pre_dispatch_handler_(new internal::PreEventDispatchHandler(this)),
    164       post_dispatch_handler_(new internal::PostEventDispatchHandler),
    165       focus_search_(this, false, false),
    166       focus_traversable_parent_(NULL),
    167       focus_traversable_parent_view_(NULL),
    168       event_dispatch_target_(NULL),
    169       old_dispatch_target_(NULL) {
    170   AddPreTargetHandler(pre_dispatch_handler_.get());
    171   AddPostTargetHandler(post_dispatch_handler_.get());
    172   SetEventTargeter(scoped_ptr<ViewTargeter>(new RootViewTargeter(this, this)));
    173 }
    174 
    175 RootView::~RootView() {
    176   // If we have children remove them explicitly so to make sure a remove
    177   // notification is sent for each one of them.
    178   if (has_children())
    179     RemoveAllChildViews(true);
    180 }
    181 
    182 // Tree operations -------------------------------------------------------------
    183 
    184 void RootView::SetContentsView(View* contents_view) {
    185   DCHECK(contents_view && GetWidget()->native_widget()) <<
    186       "Can't be called until after the native widget is created!";
    187   // The ContentsView must be set up _after_ the window is created so that its
    188   // Widget pointer is valid.
    189   SetLayoutManager(new FillLayout);
    190   if (has_children())
    191     RemoveAllChildViews(true);
    192   AddChildView(contents_view);
    193 
    194   // Force a layout now, since the attached hierarchy won't be ready for the
    195   // containing window's bounds. Note that we call Layout directly rather than
    196   // calling the widget's size changed handler, since the RootView's bounds may
    197   // not have changed, which will cause the Layout not to be done otherwise.
    198   Layout();
    199 }
    200 
    201 View* RootView::GetContentsView() {
    202   return child_count() > 0 ? child_at(0) : NULL;
    203 }
    204 
    205 void RootView::NotifyNativeViewHierarchyChanged() {
    206   PropagateNativeViewHierarchyChanged();
    207 }
    208 
    209 // Focus -----------------------------------------------------------------------
    210 
    211 void RootView::SetFocusTraversableParent(FocusTraversable* focus_traversable) {
    212   DCHECK(focus_traversable != this);
    213   focus_traversable_parent_ = focus_traversable;
    214 }
    215 
    216 void RootView::SetFocusTraversableParentView(View* view) {
    217   focus_traversable_parent_view_ = view;
    218 }
    219 
    220 // System events ---------------------------------------------------------------
    221 
    222 void RootView::ThemeChanged() {
    223   View::PropagateThemeChanged();
    224 }
    225 
    226 void RootView::LocaleChanged() {
    227   View::PropagateLocaleChanged();
    228 }
    229 
    230 ////////////////////////////////////////////////////////////////////////////////
    231 // RootView, FocusTraversable implementation:
    232 
    233 FocusSearch* RootView::GetFocusSearch() {
    234   return &focus_search_;
    235 }
    236 
    237 FocusTraversable* RootView::GetFocusTraversableParent() {
    238   return focus_traversable_parent_;
    239 }
    240 
    241 View* RootView::GetFocusTraversableParentView() {
    242   return focus_traversable_parent_view_;
    243 }
    244 
    245 ////////////////////////////////////////////////////////////////////////////////
    246 // RootView, ui::EventProcessor overrides:
    247 
    248 ui::EventTarget* RootView::GetRootTarget() {
    249   return this;
    250 }
    251 
    252 ui::EventDispatchDetails RootView::OnEventFromSource(ui::Event* event) {
    253   if (event->IsKeyEvent())
    254     return EventProcessor::OnEventFromSource(event);
    255 
    256   if (event->IsScrollEvent())
    257     return EventProcessor::OnEventFromSource(event);
    258 
    259   if (event->IsGestureEvent()) {
    260     // TODO(tdanderson): Once DispatchGestureEvent() has been removed, move
    261     //                   all of this logic into an override of a new
    262     //                   virtual method
    263     //                   EventProcessor::OnEventProcessingStarted() (which
    264     //                   returns false if no processing should take place).
    265     //                   Also move the implementation of
    266     //                   PrepareEventForDispatch() into this new method.
    267     //                   Then RootView::OnEventFromSource() can be removed.
    268     ui::GestureEvent* gesture_event = event->AsGestureEvent();
    269 
    270     // Do not dispatch ui::ET_GESTURE_BEGIN events.
    271     if (gesture_event->type() == ui::ET_GESTURE_BEGIN)
    272       return DispatchDetails();
    273 
    274     // Ignore ui::ET_GESTURE_END events which do not correspond to the
    275     // removal of the final touch point.
    276     if (gesture_event->type() == ui::ET_GESTURE_END &&
    277         gesture_event->details().touch_points() > 1) {
    278       return DispatchDetails();
    279     }
    280 
    281     // Ignore subsequent gesture scroll events if no handler was set for a
    282     // ui::ET_GESTURE_SCROLL_BEGIN event.
    283     if (!gesture_handler_ &&
    284         (gesture_event->type() == ui::ET_GESTURE_SCROLL_UPDATE ||
    285          gesture_event->type() == ui::ET_GESTURE_SCROLL_END ||
    286          gesture_event->type() == ui::ET_SCROLL_FLING_START)) {
    287       return DispatchDetails();
    288     }
    289 
    290     gesture_handler_set_before_processing_ = !!gesture_handler_;
    291     return EventProcessor::OnEventFromSource(event);
    292   }
    293 
    294   if (event->IsTouchEvent())
    295     NOTREACHED() << "Touch events should not be sent to RootView.";
    296 
    297   if (event->IsMouseEvent())
    298     NOTREACHED() << "Should not be called with a MouseEvent.";
    299 
    300   return DispatchDetails();
    301 }
    302 
    303 void RootView::OnEventProcessingFinished(ui::Event* event) {
    304   // If |event| was not handled and |gesture_handler_| was not set by the
    305   // dispatch of a previous gesture event, then no default gesture handler
    306   // should be set prior to the next gesture event being received.
    307   if (event->IsGestureEvent() &&
    308       !event->handled() &&
    309       !gesture_handler_set_before_processing_) {
    310     gesture_handler_ = NULL;
    311   }
    312 }
    313 
    314 ////////////////////////////////////////////////////////////////////////////////
    315 // RootView, View overrides:
    316 
    317 const Widget* RootView::GetWidget() const {
    318   return widget_;
    319 }
    320 
    321 Widget* RootView::GetWidget() {
    322   return const_cast<Widget*>(const_cast<const RootView*>(this)->GetWidget());
    323 }
    324 
    325 bool RootView::IsDrawn() const {
    326   return visible();
    327 }
    328 
    329 void RootView::Layout() {
    330   View::Layout();
    331   widget_->OnRootViewLayout();
    332 }
    333 
    334 const char* RootView::GetClassName() const {
    335   return kViewClassName;
    336 }
    337 
    338 void RootView::SchedulePaintInRect(const gfx::Rect& rect) {
    339   if (layer()) {
    340     layer()->SchedulePaint(rect);
    341   } else {
    342     gfx::Rect xrect = ConvertRectToParent(rect);
    343     gfx::Rect invalid_rect = gfx::IntersectRects(GetLocalBounds(), xrect);
    344     if (!invalid_rect.IsEmpty())
    345       widget_->SchedulePaintInRect(invalid_rect);
    346   }
    347 }
    348 
    349 bool RootView::OnMousePressed(const ui::MouseEvent& event) {
    350   UpdateCursor(event);
    351   SetMouseLocationAndFlags(event);
    352 
    353   // If mouse_pressed_handler_ is non null, we are currently processing
    354   // a pressed -> drag -> released session. In that case we send the
    355   // event to mouse_pressed_handler_
    356   if (mouse_pressed_handler_) {
    357     ui::MouseEvent mouse_pressed_event(event, static_cast<View*>(this),
    358                                        mouse_pressed_handler_);
    359     drag_info_.Reset();
    360     ui::EventDispatchDetails dispatch_details =
    361         DispatchEvent(mouse_pressed_handler_, &mouse_pressed_event);
    362     if (dispatch_details.dispatcher_destroyed)
    363       return true;
    364     return true;
    365   }
    366   DCHECK(!explicit_mouse_handler_);
    367 
    368   bool hit_disabled_view = false;
    369   // Walk up the tree until we find a view that wants the mouse event.
    370   for (mouse_pressed_handler_ = GetEventHandlerForPoint(event.location());
    371        mouse_pressed_handler_ && (mouse_pressed_handler_ != this);
    372        mouse_pressed_handler_ = mouse_pressed_handler_->parent()) {
    373     DVLOG(1) << "OnMousePressed testing "
    374         << mouse_pressed_handler_->GetClassName();
    375     if (!mouse_pressed_handler_->enabled()) {
    376       // Disabled views should eat events instead of propagating them upwards.
    377       hit_disabled_view = true;
    378       break;
    379     }
    380 
    381     // See if this view wants to handle the mouse press.
    382     ui::MouseEvent mouse_pressed_event(event, static_cast<View*>(this),
    383                                        mouse_pressed_handler_);
    384 
    385     // Remove the double-click flag if the handler is different than the
    386     // one which got the first click part of the double-click.
    387     if (mouse_pressed_handler_ != last_click_handler_)
    388       mouse_pressed_event.set_flags(event.flags() & ~ui::EF_IS_DOUBLE_CLICK);
    389 
    390     drag_info_.Reset();
    391     ui::EventDispatchDetails dispatch_details =
    392         DispatchEvent(mouse_pressed_handler_, &mouse_pressed_event);
    393     if (dispatch_details.dispatcher_destroyed)
    394       return mouse_pressed_event.handled();
    395 
    396     // The view could have removed itself from the tree when handling
    397     // OnMousePressed().  In this case, the removal notification will have
    398     // reset mouse_pressed_handler_ to NULL out from under us.  Detect this
    399     // case and stop.  (See comments in view.h.)
    400     //
    401     // NOTE: Don't return true here, because we don't want the frame to
    402     // forward future events to us when there's no handler.
    403     if (!mouse_pressed_handler_)
    404       break;
    405 
    406     // If the view handled the event, leave mouse_pressed_handler_ set and
    407     // return true, which will cause subsequent drag/release events to get
    408     // forwarded to that view.
    409     if (mouse_pressed_event.handled()) {
    410       last_click_handler_ = mouse_pressed_handler_;
    411       DVLOG(1) << "OnMousePressed handled by "
    412           << mouse_pressed_handler_->GetClassName();
    413       return true;
    414     }
    415   }
    416 
    417   // Reset mouse_pressed_handler_ to indicate that no processing is occurring.
    418   mouse_pressed_handler_ = NULL;
    419 
    420   // In the event that a double-click is not handled after traversing the
    421   // entire hierarchy (even as a single-click when sent to a different view),
    422   // it must be marked as handled to avoid anything happening from default
    423   // processing if it the first click-part was handled by us.
    424   if (last_click_handler_ && (event.flags() & ui::EF_IS_DOUBLE_CLICK))
    425     hit_disabled_view = true;
    426 
    427   last_click_handler_ = NULL;
    428   return hit_disabled_view;
    429 }
    430 
    431 bool RootView::OnMouseDragged(const ui::MouseEvent& event) {
    432   if (mouse_pressed_handler_) {
    433     SetMouseLocationAndFlags(event);
    434 
    435     ui::MouseEvent mouse_event(event, static_cast<View*>(this),
    436                                mouse_pressed_handler_);
    437     ui::EventDispatchDetails dispatch_details =
    438         DispatchEvent(mouse_pressed_handler_, &mouse_event);
    439     if (dispatch_details.dispatcher_destroyed)
    440       return false;
    441   }
    442   return false;
    443 }
    444 
    445 void RootView::OnMouseReleased(const ui::MouseEvent& event) {
    446   UpdateCursor(event);
    447 
    448   if (mouse_pressed_handler_) {
    449     ui::MouseEvent mouse_released(event, static_cast<View*>(this),
    450                                   mouse_pressed_handler_);
    451     // We allow the view to delete us from the event dispatch callback. As such,
    452     // configure state such that we're done first, then call View.
    453     View* mouse_pressed_handler = mouse_pressed_handler_;
    454     SetMouseHandler(NULL);
    455     ui::EventDispatchDetails dispatch_details =
    456         DispatchEvent(mouse_pressed_handler, &mouse_released);
    457     if (dispatch_details.dispatcher_destroyed)
    458       return;
    459   }
    460 }
    461 
    462 void RootView::OnMouseCaptureLost() {
    463   // TODO: this likely needs to reset touch handler too.
    464 
    465   if (mouse_pressed_handler_ || gesture_handler_) {
    466     // Synthesize a release event for UpdateCursor.
    467     if (mouse_pressed_handler_) {
    468       gfx::Point last_point(last_mouse_event_x_, last_mouse_event_y_);
    469       ui::MouseEvent release_event(ui::ET_MOUSE_RELEASED,
    470                                    last_point, last_point,
    471                                    last_mouse_event_flags_,
    472                                    0);
    473       UpdateCursor(release_event);
    474     }
    475     // We allow the view to delete us from OnMouseCaptureLost. As such,
    476     // configure state such that we're done first, then call View.
    477     View* mouse_pressed_handler = mouse_pressed_handler_;
    478     View* gesture_handler = gesture_handler_;
    479     SetMouseHandler(NULL);
    480     if (mouse_pressed_handler)
    481       mouse_pressed_handler->OnMouseCaptureLost();
    482     else
    483       gesture_handler->OnMouseCaptureLost();
    484     // WARNING: we may have been deleted.
    485   }
    486 }
    487 
    488 void RootView::OnMouseMoved(const ui::MouseEvent& event) {
    489   View* v = GetEventHandlerForPoint(event.location());
    490   // Find the first enabled view, or the existing move handler, whichever comes
    491   // first.  The check for the existing handler is because if a view becomes
    492   // disabled while handling moves, it's wrong to suddenly send ET_MOUSE_EXITED
    493   // and ET_MOUSE_ENTERED events, because the mouse hasn't actually exited yet.
    494   while (v && !v->enabled() && (v != mouse_move_handler_))
    495     v = v->parent();
    496   if (v && v != this) {
    497     if (v != mouse_move_handler_) {
    498       if (mouse_move_handler_ != NULL &&
    499           (!mouse_move_handler_->notify_enter_exit_on_child() ||
    500            !mouse_move_handler_->Contains(v))) {
    501         MouseEnterExitEvent exit(event, ui::ET_MOUSE_EXITED);
    502         exit.ConvertLocationToTarget(static_cast<View*>(this),
    503                                      mouse_move_handler_);
    504         ui::EventDispatchDetails dispatch_details =
    505             DispatchEvent(mouse_move_handler_, &exit);
    506         if (dispatch_details.dispatcher_destroyed)
    507           return;
    508         NotifyEnterExitOfDescendant(event, ui::ET_MOUSE_EXITED,
    509             mouse_move_handler_, v);
    510       }
    511       View* old_handler = mouse_move_handler_;
    512       mouse_move_handler_ = v;
    513       if (!mouse_move_handler_->notify_enter_exit_on_child() ||
    514           !mouse_move_handler_->Contains(old_handler)) {
    515         MouseEnterExitEvent entered(event, ui::ET_MOUSE_ENTERED);
    516         entered.ConvertLocationToTarget(static_cast<View*>(this),
    517                                         mouse_move_handler_);
    518         ui::EventDispatchDetails dispatch_details =
    519             DispatchEvent(mouse_move_handler_, &entered);
    520         if (dispatch_details.dispatcher_destroyed)
    521           return;
    522         NotifyEnterExitOfDescendant(event, ui::ET_MOUSE_ENTERED,
    523             mouse_move_handler_, old_handler);
    524       }
    525     }
    526     ui::MouseEvent moved_event(event, static_cast<View*>(this),
    527                                mouse_move_handler_);
    528     mouse_move_handler_->OnMouseMoved(moved_event);
    529     // TODO(tdanderson): It may be possible to avoid setting the cursor twice
    530     //                   (once here and once from CompoundEventFilter) on a
    531     //                   mousemove. See crbug.com/351469.
    532     if (!(moved_event.flags() & ui::EF_IS_NON_CLIENT))
    533       widget_->SetCursor(mouse_move_handler_->GetCursor(moved_event));
    534   } else if (mouse_move_handler_ != NULL) {
    535     MouseEnterExitEvent exited(event, ui::ET_MOUSE_EXITED);
    536     ui::EventDispatchDetails dispatch_details =
    537         DispatchEvent(mouse_move_handler_, &exited);
    538     if (dispatch_details.dispatcher_destroyed)
    539       return;
    540     NotifyEnterExitOfDescendant(event, ui::ET_MOUSE_EXITED,
    541         mouse_move_handler_, v);
    542     // On Aura the non-client area extends slightly outside the root view for
    543     // some windows.  Let the non-client cursor handling code set the cursor
    544     // as we do above.
    545     if (!(event.flags() & ui::EF_IS_NON_CLIENT))
    546       widget_->SetCursor(gfx::kNullCursor);
    547     mouse_move_handler_ = NULL;
    548   }
    549 }
    550 
    551 void RootView::OnMouseExited(const ui::MouseEvent& event) {
    552   if (mouse_move_handler_ != NULL) {
    553     MouseEnterExitEvent exited(event, ui::ET_MOUSE_EXITED);
    554     ui::EventDispatchDetails dispatch_details =
    555         DispatchEvent(mouse_move_handler_, &exited);
    556     if (dispatch_details.dispatcher_destroyed)
    557       return;
    558     NotifyEnterExitOfDescendant(event, ui::ET_MOUSE_EXITED,
    559         mouse_move_handler_, NULL);
    560     mouse_move_handler_ = NULL;
    561   }
    562 }
    563 
    564 bool RootView::OnMouseWheel(const ui::MouseWheelEvent& event) {
    565   for (View* v = GetEventHandlerForPoint(event.location());
    566        v && v != this && !event.handled(); v = v->parent()) {
    567     ui::EventDispatchDetails dispatch_details =
    568         DispatchEvent(v, const_cast<ui::MouseWheelEvent*>(&event));
    569     if (dispatch_details.dispatcher_destroyed ||
    570         dispatch_details.target_destroyed) {
    571       return event.handled();
    572     }
    573   }
    574   return event.handled();
    575 }
    576 
    577 void RootView::SetMouseHandler(View* new_mh) {
    578   // If we're clearing the mouse handler, clear explicit_mouse_handler_ as well.
    579   explicit_mouse_handler_ = (new_mh != NULL);
    580   mouse_pressed_handler_ = new_mh;
    581   gesture_handler_ = new_mh;
    582   drag_info_.Reset();
    583 }
    584 
    585 void RootView::GetAccessibleState(ui::AXViewState* state) {
    586   state->name = widget_->widget_delegate()->GetAccessibleWindowTitle();
    587   state->role = widget_->widget_delegate()->GetAccessibleWindowRole();
    588 }
    589 
    590 void RootView::UpdateParentLayer() {
    591   if (layer())
    592     ReparentLayer(gfx::Vector2d(GetMirroredX(), y()), widget_->GetLayer());
    593 }
    594 
    595 ////////////////////////////////////////////////////////////////////////////////
    596 // RootView, protected:
    597 
    598 void RootView::ViewHierarchyChanged(
    599     const ViewHierarchyChangedDetails& details) {
    600   widget_->ViewHierarchyChanged(details);
    601 
    602   if (!details.is_add) {
    603     if (!explicit_mouse_handler_ && mouse_pressed_handler_ == details.child)
    604       mouse_pressed_handler_ = NULL;
    605     if (mouse_move_handler_ == details.child)
    606       mouse_move_handler_ = NULL;
    607     if (gesture_handler_ == details.child)
    608       gesture_handler_ = NULL;
    609     if (event_dispatch_target_ == details.child)
    610       event_dispatch_target_ = NULL;
    611     if (old_dispatch_target_ == details.child)
    612       old_dispatch_target_ = NULL;
    613   }
    614 }
    615 
    616 void RootView::VisibilityChanged(View* /*starting_from*/, bool is_visible) {
    617   if (!is_visible) {
    618     // When the root view is being hidden (e.g. when widget is minimized)
    619     // handlers are reset, so that after it is reshown, events are not captured
    620     // by old handlers.
    621     explicit_mouse_handler_ = false;
    622     mouse_pressed_handler_ = NULL;
    623     mouse_move_handler_ = NULL;
    624     gesture_handler_ = NULL;
    625     event_dispatch_target_ = NULL;
    626     old_dispatch_target_ = NULL;
    627   }
    628 }
    629 
    630 void RootView::OnPaint(gfx::Canvas* canvas) {
    631   if (!layer() || !layer()->fills_bounds_opaquely())
    632     canvas->DrawColor(SK_ColorBLACK, SkXfermode::kClear_Mode);
    633 
    634   View::OnPaint(canvas);
    635 }
    636 
    637 gfx::Vector2d RootView::CalculateOffsetToAncestorWithLayer(
    638     ui::Layer** layer_parent) {
    639   gfx::Vector2d offset(View::CalculateOffsetToAncestorWithLayer(layer_parent));
    640   if (!layer() && layer_parent)
    641     *layer_parent = widget_->GetLayer();
    642   return offset;
    643 }
    644 
    645 View::DragInfo* RootView::GetDragInfo() {
    646   return &drag_info_;
    647 }
    648 
    649 ////////////////////////////////////////////////////////////////////////////////
    650 // RootView, private:
    651 
    652 // Input -----------------------------------------------------------------------
    653 
    654 void RootView::UpdateCursor(const ui::MouseEvent& event) {
    655   if (!(event.flags() & ui::EF_IS_NON_CLIENT)) {
    656     View* v = GetEventHandlerForPoint(event.location());
    657     ui::MouseEvent me(event, static_cast<View*>(this), v);
    658     widget_->SetCursor(v->GetCursor(me));
    659   }
    660 }
    661 
    662 void RootView::SetMouseLocationAndFlags(const ui::MouseEvent& event) {
    663   last_mouse_event_flags_ = event.flags();
    664   last_mouse_event_x_ = event.x();
    665   last_mouse_event_y_ = event.y();
    666 }
    667 
    668 void RootView::NotifyEnterExitOfDescendant(const ui::MouseEvent& event,
    669                                            ui::EventType type,
    670                                            View* view,
    671                                            View* sibling) {
    672   for (View* p = view->parent(); p; p = p->parent()) {
    673     if (!p->notify_enter_exit_on_child())
    674       continue;
    675     if (sibling && p->Contains(sibling))
    676       break;
    677     // It is necessary to recreate the notify-event for each dispatch, since one
    678     // of the callbacks can mark the event as handled, and that would cause
    679     // incorrect event dispatch.
    680     MouseEnterExitEvent notify_event(event, type);
    681     ui::EventDispatchDetails dispatch_details = DispatchEvent(p, &notify_event);
    682     if (dispatch_details.dispatcher_destroyed ||
    683         dispatch_details.target_destroyed) {
    684       return;
    685     }
    686   }
    687 }
    688 
    689 bool RootView::CanDispatchToTarget(ui::EventTarget* target) {
    690   return event_dispatch_target_ == target;
    691 }
    692 
    693 ui::EventDispatchDetails RootView::PreDispatchEvent(ui::EventTarget* target,
    694                                                     ui::Event* event) {
    695   View* view = static_cast<View*>(target);
    696   if (event->IsGestureEvent()) {
    697     // Update |gesture_handler_| to indicate which View is currently handling
    698     // gesture events.
    699     // TODO(tdanderson): Look into moving this to PostDispatchEvent() and
    700     //                   using |event_dispatch_target_| instead of
    701     //                   |gesture_handler_| to detect if the view has been
    702     //                   removed from the tree.
    703     gesture_handler_ = view;
    704 
    705     // Disabled views are permitted to be targets of gesture events, but
    706     // gesture events should never actually be dispatched to them. Prevent
    707     // dispatch by marking the event as handled.
    708     if (!view->enabled())
    709       event->SetHandled();
    710   }
    711 
    712   old_dispatch_target_ = event_dispatch_target_;
    713   event_dispatch_target_ = view;
    714   return DispatchDetails();
    715 }
    716 
    717 ui::EventDispatchDetails RootView::PostDispatchEvent(ui::EventTarget* target,
    718                                                      const ui::Event& event) {
    719   // The GESTURE_END event corresponding to the removal of the final touch
    720   // point marks the end of a gesture sequence, so reset |gesture_handler_|
    721   // to NULL.
    722   if (event.type() == ui::ET_GESTURE_END) {
    723     // In case a drag was in progress, reset all the handlers. Otherwise, just
    724     // reset the gesture handler.
    725     if (gesture_handler_ && gesture_handler_ == mouse_pressed_handler_)
    726       SetMouseHandler(NULL);
    727     else
    728       gesture_handler_ = NULL;
    729   }
    730 
    731   DispatchDetails details;
    732   if (target != event_dispatch_target_)
    733     details.target_destroyed = true;
    734 
    735   event_dispatch_target_ = old_dispatch_target_;
    736   old_dispatch_target_ = NULL;
    737 
    738 #ifndef NDEBUG
    739   DCHECK(!event_dispatch_target_ || Contains(event_dispatch_target_));
    740 #endif
    741 
    742   return details;
    743 }
    744 
    745 }  // namespace internal
    746 }  // namespace views
    747